The present disclosure relates to an image projection apparatus including a projection optical system, and to an image projection method using the image projection apparatus.
A projector (image projection apparatus) has been known, which includes an illumination optical system (illumination unit) using a halogen lamp, a metal halide lamp, etc. as a light source, and a projection optical system including a light modulation device and a projection lens, (for example, see Japanese Unexamined Patent Application Publication No. 2011-2611).
A small (palm-sized) and lightweight portable projector referred to as microprojector is now beginning to be widely used in such a projector field. In such a microprojector, a light emitting diode (LED) is mainly used as a light source of an illumination unit. In recent years, use of a laser draws attention in terms of expansion of a color reproduction range and reduction in power consumption.
On the other hand, there has been proposed an image projection apparatus that includes a short-focus projection lens, and is capable of selecting between projection onto a wall surface (vertical plane) and projection onto a floor face (horizontal plane) by changing a posture of the image projection apparatus (mounting surface for placement of the image projection apparatus), (for example, see Japanese Unexamined Patent Application Publication No. 2010-160476).